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  2. Curved mirror - Wikipedia

    en.wikipedia.org/wiki/Curved_mirror

    A concave mirror, or converging mirror, has a reflecting surface that is recessed inward (away from the incident light). Concave mirrors reflect light inward to one focal point. They are used to focus light. Unlike convex mirrors, concave mirrors show different image types depending on the distance between the object and the mirror.

  3. Focal length - Wikipedia

    en.wikipedia.org/wiki/Focal_length

    The main benefit of using optical power rather than focal length is that the thin lens formula has the object distance, image distance, and focal length all as reciprocals. Additionally, when relatively thin lenses are placed close together their powers approximately add. Thus, a thin 2.0-dioptre lens placed close to a thin 0.5-dioptre lens ...

  4. Real image - Wikipedia

    en.wikipedia.org/wiki/Real_image

    A real image occurs at points where rays actually converge, whereas a virtual image occurs at points that rays appear to be diverging from. Real images can be produced by concave mirrors and converging lenses, only if the object is placed further away from the mirror/lens than the focal point, and this real image is inverted. As the object ...

  5. Least distance of distinct vision - Wikipedia

    en.wikipedia.org/wiki/Least_distance_of_distinct...

    The focal point F and focal length f of a positive (convex) lens, a negative (concave) lens, a concave mirror, and a convex mirror. In optometry, the least distance of distinct vision (LDDV) or the reference seeing distance (RSD) is the closest someone with "normal" vision (20/20 vision) can comfortably look at something. [1] In other words ...

  6. Virtual image - Wikipedia

    en.wikipedia.org/wiki/Virtual_image

    The image in a plane mirror is not magnified (that is, the image is the same size as the object) and appears to be as far behind the mirror as the object is in front of the mirror. A diverging lens (one that is thicker at the edges than the middle) or a concave mirror forms a virtual image. Such an image is reduced in size when compared to the ...

  7. Spherical aberration - Wikipedia

    en.wikipedia.org/wiki/Spherical_aberration

    Spherical aberration of collimated light incident on a concave spherical mirror In optics, spherical aberration (SA) is a ... i is the image distance, ...

  8. Reflecting telescope - Wikipedia

    en.wikipedia.org/wiki/Reflecting_telescope

    A convex secondary mirror is placed just to the side of the light entering the telescope, and positioned afocally so as to send parallel light on to the tertiary. The concave tertiary mirror is positioned exactly twice as far to the side of the entering beam as was the convex secondary, and its own radius of curvature distant from the secondary.

  9. Optical telescope - Wikipedia

    en.wikipedia.org/wiki/Optical_telescope

    The basic scheme is that the primary light-gathering element, the objective (1) (the convex lens or concave mirror used to gather the incoming light), focuses that light from the distant object (4) to a focal plane where it forms a real image (5). This image may be recorded or viewed through an eyepiece (2), which acts like a magnifying glass.